Text and photos by George Franklin #20000416

1955-57 WHEEL TUBS Photo #1: The My 1956 two-door sedan project had some very rusty rear area of this car was in wheelhouses, wheel tubs, and trunk walls. The car is being customized sad shape. The rear with a street/strip flavor, so originality is not a big concern. It has already section of the original inner wheel tub had been treated to a spring pocket kit P/N 21-131 and is due for some very rusted away from the wide rear . This car needed so much sheet metal that the decision inner trunk wall. The was made to use race car-style wheel tubs and to repair the trunk walls. rusty gap was over an The final result is a whopping 16" of width clearance between the inch wide and had inside of the quarter panel lip and the original frame. been filled in by gobs of body filler. The outer rear wheelhouse section between the Tools Needed: rear quarter panel and trunk wall didn't look any better. 1/4” pilot point drill bit Sharp knife The front section of the original inner wheel tub had similar Drill Measuring tape rust problems. The outer front wheelhouse section was rusty Seam splitter C-clamps Ball peen hammer Pneumatic high speed saw as well. Rather than purchase a few thousand dollars of sheet Markers Body hammer and dollies metal to preserve the original look, the decision was made to Cut-off tool Tin snips go for a street/strip look for a lot less money. As one can see, Reciprocating saw Pneumatic hole punch this car had recently received a new floor. The rear seat back Die grinder MIG welder support will need to be removed to gain access to the tubs. Soap stone Alignment punch tools Begin by drilling out the support spot welds with a 1/4 inch Masking tape Vise-grips pilot point drill bit. Use a seam splitter to pop the welds loose, and remove the support.

31-410 31-90 Photo #2: The tub kit P/N 31- 410 has four nearly flat pieces of 24 gauge steel. These include two semi-circular cheeks and two rectangular bands. Also in the carton will be two sheets of corrugated Materials Needed: paper that will serve as band templates. Do not destroy the Weld-thru primer carton. It will be used to make Miscellaneous flat sheetmetal the cheek templates. 88-0187-1 Joint & Seam Sealer

Parts Needed: Photo #3: With the rear of the car 31-410 Wheel Tub Kit up on jack stands, remove both 31-89 1956-57 Left Rear Wheelhouse Extension rear wheels and the gas tank. 31-90 1956-57 Right Rear Wheelhouse Extension Before cutting any sheet metal Optional Parts: away, mark the inside of the 31-317 1955-57 Left Trunk Wall Repair Panel outer quarter panel along the (Htp/Cvt Only) lower edge of the wheelhouse 31-318 1955-57 Right Trunk Wall Repair Panel seal. The new wheel tub must (Htp/Cvt Only) meet the quarter panel near this 31-223 1955-57 Complete Trunk Floor line. Also mark the location and 31-276 1955-57 Complete Trunk Floor W/Braces depth of the window dimple in the front wheelhouse section. 31-81 1955 Left Rear Wheelhouse Extension This dimple allows necessary 31-82 1955 Right Rear Wheelhouse Extension clearance for the rear corner of the rear quarter window. To order parts call 1-800-456-1957 or visit ClassicChevy.com Photo #4a & 4b: A cut-off tool was used to sever the support Time Frame: between the original inner wheel tub and the trunk hinge box. 40-60 hours Always use proper safety equipment. Photo #7: This was a good time to remove the paint from the lower portion of the hinge box using a 3M Green Roloc bristle disc on a pneumatic die grinder. These discs are great for removing paint without grinding #4b away too much metal. The metal on this car was already thin We used a reciprocating saw to enough! The lower portion of cut the tub from the trunk floor. the hinge box was then coated For the cuts along the inboard with weld-thru primer, SEM #4a and rear sides of the tub, cut the 39783. Rather than repeating floor and leave the floor to tub flange attached to the tub. this many times, suffice it to say that all metal pieces need to At the front of tub we preserved the outboard 8" of the floor be clean and bare prior to welding. The metal should also be flange to become an attachment point for the new tub. Drill coated with weld-thru primer if the backside metal surface will out the spot welds holding the front of the tub to the floor. not be accessible after welding. Use a seam splitter to separate the front side of the tub from the floor. Photo #8: Working from under the car, Photo #5: This is the mark the underside of preserved floor flange the trunk floor along section. This flange has the outboard edge of no holes drilled though the frame. We are it because this is a using a flat soap stone brand new floor and which left a good had never been spot visible line. welded to the original We used a cut-off tool to make cuts through the trunk floor tub. If your rear every few inches along the line. wheelhouse extensions (mud flaps) are in good shape you may want to preserve them as well. Leave them attached to the quarter panel at the rear. Cut the extensions away from the Photo #9: On the top surface of rear wheelhouse section with a horizontal cut at trunk floor the trunk floor the cuts were height. If your rear wheelhouse baffle is in good shape you connected with a length of tape might wish to preserve it too. This baffle seals the upper inner to mark a continuous cut line. quarter panel keeping dust, heat, cold, and tire smoke from This cut will be parallel to and making their way into the passenger compartment. The baffle directly above the frame's is welded to the inner trunk wall and to the top of the rear outboard edge. outer wheelhouse. Cut the baffle away from the wheelhouse, leaving it attached to the trunk wall.

Photo #6: These are the removed Photo #10: There are four vertical components of the beads rolled into the original original sheet metal inner trunk wall for strength. The from the left side of rear cut line on the trunk floor, the car. The small marked here with tape, was just piece in the middle to the rear of the forward most is the baffle. This baffle was badly rusted and new ones are (fourth) bead. This was a conser- not available for this body style. The baffle on the right side vative initial position for the cut. of this car was missing entirely. New baffles will be fabricated. The cut will be moved rearward The piece on the far left is the original rear wheelhouse later to allow fine tuning of the extension. It was in pretty good shape, but the right side one height of the new tub. This rear on this car was missing. New extensions, P/N 31-89 and 31- trunk floor cut is perpendicular to 90, will be used. the frame.

Chevy Classics January 2010 3 Photo #11: The front cut will has been marked as a reference. Conventional wisdom is that also be perpendicular to the the center line of racing tubs should be vertical and centered frame and preserves the on the rear axle. This gives maximum vertical clearance for outboard eight inches of the suspension travel and symmetrical front and rear tire original floor to the forward clearance. We instead placed the center line behind the rear inner wheel tub flange. axle and at an angle to vertical. This minimizes intrusion of the tub into the passenger compartment and retains proper rear quarter window clearance, while still leaving plenty of tire clearance. The upper surface of the new tub should end up just below the trunk hinge box, although it sits lower than in Photo #12: The rusted this view. You can just see the hinge box at the top center of part of the trunk wall must this photo. The conservative rear trunk floor cut made earlier also be removed. We used can now be reassessed. By gradually moving this cut line to tape to mark a one inch the rear, the cheek template can rise higher in the trunk. The border around the rusted goal is for the cheek template to end up just below the trunk edge. We cut along the hinge box. outside of this tape line in order to reach solid metal. Cut away as much or as Photo #16: Measure little metal as needed. from the cheek template to the inside of the quarter panel at Photo #13: As the every inch mark around rusted metal was the circumference. removed we found the Keep the tape measure original location of the perpendicular to the baffle. The arrow marks cheek template and that location, just parallel to the ground. forward of the hinge Record these measurements on the cheek template. These box on the outboard measurements determine the width of the band. side of this panel. You will want to mount the new baffle in this same location.

Photo #17: Curl the band Photo #14: Make a template of template provided in the kit the tub cheek using the carton by rolling it around a that the tub kit came in. Trace cylindrical object. A the shape of the metal cheek propane bottle was used onto the carton and cut the here. template out with a sharp knife. Make a mark every inch along the circumference of the template.

Photo #18: Remove the cheek template from the car. Use Photo #15: Raise the masking tape to attach the band cheek template up template to the cheek template. into the opening in Transfer the recorded measure- the trunk floor with ments to the band and connect the inch markings on them to mark a cut line along the the inboard side. Use band. In order to make trial C-clamps to hold the fitting of the tub template easier, template to the we cut the band about one frame. The center quarter inch short of this line. line of the template Photo #19: Working from make sure it had a nice 90 degree angle. The lip of the cheek above, place the tub fits into the seam on the band, so checking these areas first is template in the trunk and recommended. We also recommend at least two people for attach it to the frame with handling this awkward job. C-clamps. The top of the band template should end Photo #23: We slid the end of up about 1/2 inch below cheek lip into the band seam the hinge box. The tub and bent the band up slightly template can be raised by with a body hammer, locking gradually increasing the length of the trunk opening. Making the cheek into the seam. Tap new rear trunk floor cuts will allow this. Notice the final cut in the seam up just enough to this photo is about 3" to the rear of the conservative initial cut. hold the cheek and band This final cut is just ahead of the third trunk wall bead. together. Gradually work your way down the seam locking in Photo #20: When the tub a few inches at a time. template is properly located it will be below and to the rear of the window dimple marking. Photo #24: After the entire This will allow proper circumference of the cheek is operation of the rear locked to the band, the seam can quarter window. Also be gradually flattened. By make sure the template working a bit at a time the seam position will not interfere with holes used to attach the will be flat and free of kinks. exterior stainless trim. Finish the seam with a hammer and dolly. Photo #21: A contour marking tool allowed us to make a more accurate band fit. The tool was made from a wooden Photo #25: The cheek paint paddle with holes template was then cut drilled at one and two along the line marking inches from its end. the top of the trunk These holes allow the tip of a marker to pass through the tool. floor. The piece of the The contour tool was slid along the inner quarter marking a cheek template cut away line on the underside of the band template. This marked line was saved to later serve followed the exact contour of quarter panel and was exactly as a guide for flange one inch from that surface. If the band template was cut too construction. The tub narrow, the two inch hole on the tool could be used instead. template was placed With the tub template in its final position this is a good time to inside the newly assembled metal tub and the trunk floor line mark the inboard side of the cheek template along the top of of the template was traced. the trunk floor. Photo #26: The contour Photo ##22: Next we tool was used to trace the assembled the actual steel tub exact contour of the inner by mating a band to a cheek. quarter panel surface We rolled the band around a onto the band. The front to give it a bit of a and rear edges of the curve. Make sure the open band template were part of the Pittsburgh seam is traced as well. At this to the inside of the curve. We point a decision must to also ran a small screwdriver down the seam to make sure it be made on how the wasn't pinched flat by the curving process. We used a hammer band will be attached to the inner surface of the rear quarter and dolly to check the lip on the curved edge of the cheek to panel. If these tubs are going into a car with a nice paint job, then this marked line will be a cut line, and the band will be Photo #29: Using the shape of glued and sealed to the quarter with autobody sealant alone. the original baffle as a guide, a This car wasn't painted, so the decision was made to make tabs template for a new baffle was that would allow spot welding of the band to the inner surface cut from cardboard. The of the quarter panel. This method will be significantly stronger placement for the baffle will be than just using sealant alone. A second line was drawn using just rear of the peak of the the contour tool, one inch further from the cheek than the band, insuring that water cannot first line. This second line became the cut line using a become trapped against the pneumatic high speed saw. The cheek was then cut along the baffle as it is thrown up into the line marking the trunk floor surface. The front and rear edges rear tail light area by the tires. of the band were cut one inch long. These long edges will This template is purposefully cut extend below the trunk floor when the tub is in place. They long with its lower edge below will become attachment points for the wheelhouse extension the line marking the at the rear and for a patch panel that will seal the passenger wheelhouse seal. The lower edge will be trimmed for a tight fit compartment floor and quarter panel at the front. to the top of the band. The new baffle was cut from a flat piece of 18 gauge sheet metal. It was tack welded to the quarter panel and to trunk Photo #27: Tabs wall with a MIG welder. The tub was then fitted and the lower were made by edge of the baffle was trimmed for a tight fit to the band. Once cutting out triangle we were satisfied with the fit, the baffle was sealed along its shaped pieces using upper edge with sealer P/N 88-0187-1. After the tub is tin snips. The welded into place and the trunk wall is repaired, the rest of the triangles were one perimeter of the baffle can be sealed. inch deep, one inch across their bases, and one inch apart. A pneumatic hole punch was used to make 3/16” holes for spot welds, two inches apart. Pliers were used to bend the tabs down along the first contour line and then the tabs were flattened with a hammer and dolly. The cardboard template shown was used to keep the tab spacing consistent.

#30a #30b Photo #28: Working Photo #30a & 30b: The underside of the trunk floor along the from above, the tub cut lines was cleaned to bare metal and the tub was lowered was trial fitted to the into place one final time. When the fit was satisfactory the tub car. The top surface was tack welded to the trunk floor from underneath. The band was checked with a was tack welded to the baffle from above. level. Make sure the A few of the tabs were spot welded to the inside of the quarter band is behind and panel. The line marking the edge of the wheelhouse seal is no below the window longer visible in this photo. That surface was prepped and is dimple and doesn’t now covered in a layer of weld-thru primer. interfere with any trim mounting holes. Slight adjustment of the tabs might be necessary to create a snug fit between the tub and the inner surface of the quarter panel. Be careful when moving the tub in and out of the trunk floor. The thin sheet metal tub can Photo #31: More tack easily bend or kink. welds were added along the floor to cheek edge. Photo #32a & 32b: The Photo #35: The inner quarter portion of the cheek panel was then rebuilt. This template that was cut panel consists mostly of flat away and saved became sheet metal. Paper templates a trunk floor contour were made and metal patches guide for making a were cut out of 18 gauge sheet flange. The flange will metal. One of the templates is help strengthen the shown taped to the quarter #32a joint between the floor panel just above its patch. and the tub. Twenty These patches were tack gauge sheet metal was welded into place on the chosen as a compromise quarter panel. Once tack between the 18 gauge welded into place they could floor and the 24 gauge be adjusted, tack welded to tub. Pieces 1-1/2” wide each other, and tack welded to the band. The patch at the were bent into 90 degree peak of the band was welded to the new baffle. The level of angles, 3/4” x 3/4”, using a #32b finish for these welds is a matter of personal preference. These sheet metal bending brake will be covered by upholstered side panels so perfect finish If you don’t have a brake, a bench vise can be used as well. work is not needed. Cuts and notches made by tin snips allowed bending the flange along the floor's contour. Photo #36: The repair of The flange was punched with holes every two to three inches the inner trunk wall was and spot welded to both the floor and the cheek. more complicated since patch panels are not available for sedan body styles. The end of the fourth bead was compro- mised by rust and had to be cut away. We began by fabricating this patch panel first. Starting with a piece of 18 gauge sheet metal approximately 6 x 12 inches, we marked a #33a #33b straight line ending in a "T" to serve as a guide. Using the small 1/4 inch die on a bead roller, we rolled a bead that ended at Photo #33a & 33b: At the front of the band there will be a gap the "T". With a straight bead established, we moved on to between the band, the passenger compartment floor, and the larger dies, making the bead wider and deeper. Since most of rear quarter panel. A cardboard template was cut to fit the gap. you may not have a bead roller, this shape can also be formed The template was used to cut a patch panel out of a piece of 18 with a ball peen hammer and some elbow grease. gauge sheet metal. The metal was tack welded into place, then The patch panel was then tack welded into place. The new welded solid with a continuous bead. The edge of the patch bead ties in nicely to the original bead above it. The remainder along the quarter panel will be sealed with autobody sealant, as of the trunk wall pieces were made by similar processes and will the band. then welded into place. If you are working on a 2-door hardtop or convertible, you can avoid making your own Photo #34: A patches and use repair panels P/N 31-317 and 31-318 here. pedestal was constructed to support the trunk Photo #37: With the hinge box and to trunk wall and inner strengthen the tub. quarter repaired, The sides of the flanges should be made pedestal extend the to attach the front and walls of the hinge rear edges of the band box down to the to the floor. Shown band. Paper templates were used to create the four sides. here is a paper The templates were transferred to 18 gauge sheet metal and template that was used the pedestal sides were tack welded to both the hinge box and as guide to make the the band. cuts and notches on the flange material. Holes were punched in the flanges and they were spot welded to the band and the Photo #40: The seat back floor. With the tub tack welded in place, and all the flanges in support was then modified to fit place, the tub was then welded with a continuous bead all the around the new larger wheel way around the trunk floor. We made sure to weld only in tubs. I began by tracing the left short bursts to keep the heat down and to avoid warping the side of the support onto a piece band or the cheek. of corrugated paper. I cut out the template which included the holes that marked the original Photo #38: With the tub finished spot welds. The right side was we then tackled the rear tackled in a similar manner at the wheelhouse extension. The same time. extensions, P/N 31-89 and 31- With the support template 90, are sturdy pieces of metal positioned by alignment tools and they do take considerable through the original spot weld holes, the template was abuse. The extension is also the trimmed to fit nicely around the new wheel tub. lower stabilizing point for the rear quarter panel, keeping the quarter panel from flexing and Photo #41: The template outline fatiguing. Simply welding the was then transferred to the extension to the thin 24 gauge support and the excess metal tub band without bracing of was removed with a cut-off tool. some kind wouldn’t have been stable enough. This would be Additional trimming was especially true if the band was not spot welded to the inner necessary to give the best fit of rear quarter and was held on only by sealant. We first the support to the tub. The reinforced the extension by welding two pieces of 12 gauge support was then welded into sheet metal to the back side of the extension. These will not place using the original spot be visible from most angles. The triangular reinforcement weld holes in the package tray piece is evident from the spot welds visible on the inboard and along the rear of the floor. underside of this extension. A second piece of 12 gauge was welded to the upper surface of the trailing edge where the extension would be welded to the inner surface of the rear quarter panel. #42a Photo #42a & 42b: Flanges were made to fit along the vertical inboard side to the cheek as well as across Photo #39: A piece of 12 gauge the top of the band. A piece of sheet approximately 3 x 4 inches in metal was added to the support to size was welded to the outboard fill in the quarter circle shaped gap surface of the inner trunk wall. left by the missing original inner This piece reinforced the wall wheel tub. This increase the flange and spread the load over a larger length and strength across the top of area. Braces of 1/8 x 3/4 x 3/4 the band. As one can see by the angle were welded in place amount of metal cut from this between the trunk wall support, modifica- #42b reinforcement and the reinforced tions will need to portions of the extension. This be made to the rear bracing will keep the extension seat bottom and in place, will prevent the rear backrest frames, quarter panel from flexing, and will take the strain off the band. the seat upholstery, Be sure to mock up the gas tank filler tube to check clearances and to the side before welding these braces in place. The right side wheel tub panel. With the was then constructed using techniques similar to those shown metal work in the steps above. When the right side hinge box support was complete, a generous bead of autobody sealant along the removed, the car lost the forward mounting bracket for the underside of the Pittsburgh seam and along the edges of the original equipment jack. I have chosen to forgo the original band will keep out the elements. The underside of the tubs jack for a more compact modern jack that will be hidden can then be painted or undercoated for a finished appearance. behind custom trunk panels. For that reason the rear jack The only question now is how wide do we want the new rear bracket on the trunk floor was also removed. tires to be? Good Luck.